Unpatched Langflow Flaw CVE-2026-5027 Exploited for Unauthenticated RCE
A critical vulnerability, CVE-2026-5027, in the Langflow low-code platform has been actively exploited, allowing for remote code execution due to a lack of input sanitization. This flaw, combined with unauthenticated auto-login, has enabled attackers to write files to arbitrary locations on victim systems. The exploitation highlights a growing risk for organizations utilizing AI development tools.
The vulnerability, discovered by Tenable and subsequently reported by VulnCheck, resides in the Langflow platform's API endpoint for handling file uploads. Specifically, the 'POST /api/v2/files' endpoint fails to properly validate the 'filename' parameter, opening the door for attackers to leverage path traversal techniques – such as '../' – to write files to unauthorized locations on the system's file system. This allows for remote code execution, a particularly dangerous outcome. The vulnerability is compounded by Langflow's default unauthenticated auto-login feature, which eliminates the need for any credentials to access the vulnerable endpoint and obtain a valid session token.